Conventional one piece child resistant caps such as shown in U.S. Pat. Nos. 3,941,268 and 4,117,945, have locking means which are released by squeezing the cap. However, the locking means employed have a loose fit which permits considerable movement of the cap without unlocking it, which movement may loosen the cap sufficiently to cause leakage if the cap is tipped, thereby defeating the purpose of the cap which is to prevent unauthorized delivery of the contents.